<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
  <script src="./lib/vue-2.4.0.js"></script>
</head>

<body>
  <div id="app">
    <!-- prevent 阻止默认事件 -->
    <a href="#" @click.prevent='flag=true'>登录</a>
    <a href="#" @click.prevent='flag=false'>注册</a>
    <login v-if='flag'></login>
    <register v-else='flag'></register>
  </div>

  <script>
    Vue.component('login', {
      template: '<h3>登录</h3>'
    })
    Vue.component('register', {
      template: '<h3>注册</h3>'
    })

    var vm = new Vue({
      el: '#app',
      data: {
        flag: true 
      },
      methods: {}
    });
  </script>
</body>

</html>